4-Hydroperoxyifosfamide (HOO-IFOS) is a stable, pre-activated form (peroxide) of 4-HO-IFOS, the initial metabolite of Ifosfamide (IFOS). Under physiological conditions HOO-IFOS under goes spontaneously ring opening and conversion to isophosphoramide mustard (IPM), the active cytotoxic metabolite of IFOS. The objective of the proposed research is to synthesize 4-hydroperoxyifosfamide (HOO-IFOS) in sufficient quantity to document and validate purity and stability. A lyophilized product will be prepared at The University of Iowa, Pharmaceutical Services under GLP/GMP guidelines for clinical use in patients with advanced cancer. GC/MS and HPLC assays will be validated for quantification of bulk and pharmaceutical grade drug. Toxicology studies using a 3-day dosing regime in mice and dogs will be conducted at a GLP facility using the final product. An assay to monitor plasma HOO-IFOS PK and acrolein/chloroacetaldehyde levels in dogs receiving HOO- IFOS will be finalized. An IND package will be prepared after all the above has been finalized and submitted to the FDA. In summary - HOO-IFOS had improved anticancer activities vs. human glioblastoma and breast cancer xenografts and CPA-resistant leukemia murine models. The goal of the SBIR application will be to develop a new pro-drug, 4-hydroperoxyifosfamide (HOO-IFOS) that will generate in vivo - isophosphoramide mustard (IPM) - with reduced formation of associated toxic - chloroacetaldehyde and acrolein - by-products, normally produced during IFOS. [unreadable] [unreadable] [unreadable] [unreadable]